1. Field of the Invention
This invention relates to organosiloxane compositions that cure by a hydrosilation reaction catalyzed by a platinum group metal. More particularly, this invention relates to catalyst compositions useful for preparing one-part organosiloxane compositions that can be stored for extended periods of time yet cure at relatively low temperatures, and to a method for preparing these compositions.
2. Background Information
U.S. Pat. No. 4,584,631, which issued to G. Janik and P. Lo on Apr. 22, 1986 describes one-part storage stable organosiloxane compositions that cure by a platinum-catalyzed hydrosilation reaction. The compositions comprise a specified class of vinyl-containing polyorganosiloxanes consisting essentially of dimethylvinylsiloxane, dimethylsiloxane, trimethylsiloxy and methylsilsesquioxane units, an organohydrogensiloxane containing at least two silicon-bonded hydrogen atoms per molecule, a platinum-containing hydrosilation catalyst, and a member from a specified class of monoalkylamines and N,N,N',N'-tetraalkylalkylenediamines as the catalyst inhibitor.
U.S. Pat. No. 4,791,186, which issued to G. Janik and M. Buentello on Dec. 13, 1988 describes a method for increasing the storage stability of the curable compositions described in the aforementioned Janik and Lo patent by aging a mixture of the catalyst and catalyst inhibitor for at least 14 days under ambient conditions and then combining the resultant mixture with the vinyl-containing polyorganosiloxane.
Japanese laid-open patent application (Kokai) No. 3/95267 which was published on Apr. 19, 1991 describes storage-stable one part organosiloxane compositions comprising (A) a polyorganosiloxane wherein at least 0.05 percent of the silicon-bonded hydrocarbon radicals are alkenyl radicals, (B) an organosiloxane containing at least two siloxy units of the formula HR.sub.2 SiO where R represents a substituted or unsubstituted monovalent hydrocarbon radical other than alkenyl, (C) a hydrosilation catalyst selected from metals in the platinum group of the periodic table and compounds of these metals, (D) from 2 to 20 moles per mole of the platinum group metal of a first platinum catalyst inhibitor selected from the same group as the inhibitors of the aforementioned Janik and Lo patent, and (E) at least 50 moles per mole of the platinum group metal of an acetylenic alcohol as the second platinum catalyst inhibitor. This patent publication teaches that the viscosity of a composition prepared by blending a mixture of all the ingredients (A-E) to homogeneity did not increase substantially over a six month period at room temperature.